数控弧齿铣齿机结构薄弱模态研究

RESEARCH ON WEAK MODE STRUCTURE OF CNC BEVEL GEAR MILLER

以某数控弧齿锥齿轮铣齿机为例,研究机床结构薄弱模态的确认方法,为结构改进提供依据。通过动态试验,测量机床刀具和工件间相对激振的频率响应曲线G(ω),并分析出机床结构存在两个薄弱模态振型。切削颤振试验表明,机床每一切齿走刀过程的切入和切出期间,结构系统存在不同的颤振频率,恰好和机床G(ω)的薄弱模态频率相对应。机床结构有限元和试验模态分析均验证该结构薄弱模态的存在。

Based on a special computer numerical controlled （CNC） machine tool——the spiral bevel gear miller, some dynamic experiments are done for finding out the weak structure of the machine tool. At first, the frequency response curve G（ω） of relative vibration between cutter and workpiece is obtained from the cutting experiment. The curve G（ω） indicates that the CNC spiral bevel gear miller two weak modes with two corresponding frequencies. During the cutter milling one tooth of the bevel gear, the vibrational frequencies of machine tool are different at the phase of cut-in and cut-out. These frequencies are corresponding to those of the two weakness modes. The analysis of the cutting force shows that the cut-in and cut-out moments have different directions which results in the weak modes. The existence of the modes is approved by the analysis of the CNC bevel gear miller structure using finite elements method （FEM） and experiments. This research is meaningful for the practical design of machine tool, and it provides the practical dynamic method and example in project of machine structural dynamic design.